/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: UnaryOperation.java,v 1.2.4.1 2005/09/14 21:31:44 jeffsuttor Exp $
 */
package com.sun.org.apache.xpath.internal.operations;

import com.sun.org.apache.xpath.internal.Expression;
import com.sun.org.apache.xpath.internal.ExpressionOwner;
import com.sun.org.apache.xpath.internal.XPathContext;
import com.sun.org.apache.xpath.internal.XPathVisitor;
import com.sun.org.apache.xpath.internal.objects.XObject;

/**
 * The unary operation base class.
 */
public abstract class UnaryOperation extends Expression implements ExpressionOwner {
    static final long serialVersionUID = 6536083808424286166L;

    /** The operand for the operation.
     *  @serial */
    protected Expression m_right;

    /**
     * This function is used to fixup variables from QNames to stack frame
     * indexes at stylesheet build time.
     * @param vars List of QNames that correspond to variables.  This list
     * should be searched backwards for the first qualified name that
     * corresponds to the variable reference qname.  The position of the
     * QName in the vector from the start of the vector will be its position
     * in the stack frame (but variables above the globalsTop value will need
     * to be offset to the current stack frame).
     */
    public void fixupVariables(java.util.Vector vars, int globalsSize) {
        m_right.fixupVariables(vars, globalsSize);
    }

    /**
     * Tell if this expression or it's subexpressions can traverse outside
     * the current subtree.
     *
     * @return true if traversal outside the context node's subtree can occur.
     */
    public boolean canTraverseOutsideSubtree() {

        if (null != m_right && m_right.canTraverseOutsideSubtree())
            return true;

        return false;
    }

    /**
     * Set the expression operand for the operation.
     *
     *
     * @param r The expression operand to which the unary operation will be
     *          applied.
     */
    public void setRight(Expression r) {
        m_right = r;
        r.exprSetParent(this);
    }

    /**
     * Execute the operand and apply the unary operation to the result.
     *
     *
     * @param xctxt The runtime execution context.
     *
     * @return An XObject that represents the result of applying the unary
     *         operation to the evaluated operand.
     *
     * @throws javax.xml.transform.TransformerException
     */
    public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException {

        return operate(m_right.execute(xctxt));
    }

    /**
     * Apply the operation to two operands, and return the result.
     *
     *
     * @param right non-null reference to the evaluated right operand.
     *
     * @return non-null reference to the XObject that represents the result of the operation.
     *
     * @throws javax.xml.transform.TransformerException
     */
    public abstract XObject operate(XObject right) throws javax.xml.transform.TransformerException;

    /** @return the operand of unary operation, as an Expression.
     */
    public Expression getOperand() {
        return m_right;
    }

    /**
     * @see com.sun.org.apache.xpath.internal.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)
     */
    public void callVisitors(ExpressionOwner owner, XPathVisitor visitor) {
        if (visitor.visitUnaryOperation(owner, this)) {
            m_right.callVisitors(this, visitor);
        }
    }

    /**
     * @see ExpressionOwner#getExpression()
     */
    public Expression getExpression() {
        return m_right;
    }

    /**
     * @see ExpressionOwner#setExpression(Expression)
     */
    public void setExpression(Expression exp) {
        exp.exprSetParent(this);
        m_right = exp;
    }

    /**
     * @see Expression#deepEquals(Expression)
     */
    public boolean deepEquals(Expression expr) {
        if (!isSameClass(expr))
            return false;

        if (!m_right.deepEquals(((UnaryOperation) expr).m_right))
            return false;

        return true;
    }

}
